Funding is requested for a high performance LC-TOF instrument with electrospray, nanospray and atmospheric pressure chemical ionization. An HPLC will be interfaced for use with electrospray and APCI. The orthogonal acceleration TOF analyzer provides accurate mass determinations (5ppm at m/z 609) with an externally calibrated mass range up to m/z 10,000 da. Resolution is specified as 6000. The detector, and ADC continuous digital averager, provides improved peak shapes and wider dynamic range, compared to TDC detectors. These features of the ADC allow analysis of true isotope distributions, including HID exchange product correlation of signal to sample size, e.g. through four orders of magnitude with an R=0.998. Major users propose to use the instrument to; . Identify key nucleophiles involved in self-adduct formation and target alkylation of oligonucleotides, to determine the kinetics of these processes; Characterize non-natural self assemblies constructed by hydrophobic effects, e.g. self complementary amphiphiles and self sorted molecular clips; . Analyze and localize hydrogen/deuterium exchange to characterize a key intermediate in the assembly transcriptional regulatory complex of the biotin repressor; . Characterize polyubiquitin chains, synthetic and isotope labeled analogs for subsequent NMR studies and dynamics; . Characterize intermediates in the synthesis of un-natural analogs of pancratistatin, streptonigrin and nephritogenoside. The instrument will be housed in the existing Departmental Central Instrumentation Facility, where it will be managed by the staff mass spectroscopist Mr. Noel Whittaker, and operated by him and trained users. It is anticipated that the use of the instrument by scientists working across a broad range of chemistry, biochemistry and cell biology will help stimulate cross-disciplinary discussions and collaboration.